The equation for the area of a triangle is 1/2 x base x height.
Plug in the values that you already have with h being the missing height value:
30= 1/2 x 12 x h
Simplify:
30=6h
Solve:
30/6=h
5=h
The heoght of the triangle is 5 units
Your max amount for this is $20. Let's say x represents the number of gallons.
20 ≥ 3.2x
x = 6.25 gallons
If they're asking for integers or whole numbers, you'd round down to 6 because you only have enough money for 6 full gallons. If you rounded up to 7, you wouldn't be able to fill it up completely because then you'd be over your $20.00 budget for gas.
